Thin metal films (also referred to as membranes) are useful in a broad array of devices, and especially in optical photonic devices, medical and chemical filters, x-ray lithography, and micro-electromechanical system devices ("MEMS," also referred to as micromachines). Thin metal films are also useful in enhanced light transmission apparatus, such as those disclosed in U.S. Pat. No. 5,973,316 assigned to NEC Research Institute, Inc., for example.
Recently, a need has emerged for thin metal films that are unsupported by a substrate, referred to herein as "free-standing thin metal films." Free-standing thin metal films are thin metal films that not supported by a substrate (any substantially solid material other than the thin metal film itself) over a predetermined area on either side of the metal film for mechanical stability or the like. The ability to make free-standing thin metal films opens a broad range of design possibilities in which the unique and substantial properties of metals (mechanical, structural, electrical, optical, thermal, etch resistance) may be exploited in new devices. However, due to the thinness of such metal films (typically on the order of several microns to less than a micron), manufacturing free-standing thin metal films is difficult. It is therefore desirable to provide practical and reliable methods for fabricating thin free-standing thin metal films.